If your PC uses a version of the Windows operating system (2000, ME, XP or Vista) you may have experienced the strange phenomenon of your computer starting-up by itself (booting-up by itself).

Apart from the possibility that your system may be possessed, there are a number of reasonable explanations. Let’s see if we can figure this out together.

In many cases (not every case) this problem is caused by modem settings or system wake setting in the system BIOS. BIOS is an acronym for “basic input/output system.” The BIOS stores information about various components on your computer and plays a vital role in the boot-up process. For instance, the BIOS maintains settings for the disk drive, keyboard, monitor display, boot sequence and various other components or functions. In this article, we’ll walk through the process of changing your computer’s BIOS settings. Although this is a relatively simple procedure, I encourage you to proceed with caution. It would be a good idea to print-out of the following instructions as you won’t be able to use your computer while you’re updating the BOIS.

In the event that the following suggestion doesn’t resolve your issue, I also included a number of links to other articles or post that may be helpful.

Before starting the process you should be aware that system BIOS settings aren’t always identical. They differ according to system type. The instructions below are based on the BIOS settings of a Dell Dimension 2400. Your computer’s BIOS settings may be a little different.  Overall, this is a very simple process and I’m confident that you can complete it successfully if you pay attention to detail.

Step # 1:

To enter the system BIOS, you’ll need to restart your computer and interrupt what’s known as the computer POST (Power On Self Test). If you have a Dell PC, you should be able to press the F2 key to gain access to the BIOS. If you have a different system, watch your monitor’s screen during the boot-up process to view instructions on which function key to press. The monitor will display a brief message that resembles the following:

"Press F2 to enter BIOS” or

“Press F3 to enter BIOS”

Displayed below is a list of some of the most common function keys that are used to access the system BIOS (each system utilizes a different function key):

• Delete
• F1
• F2
• F3
• F5
• F10
• Escape
• Insert
• Control + Escape
• Alt + Escape
• Control + Alt + Escape
• Control + Alt + Enter

Step # 2:

Upon entering the system BIOS, use the Up or Down arrow keys to locate a section entitled Power Management and press the enter key. Thereafter, If you have a Dell computer, use the Up or Down arrow keys to locate a section entitled Auto Power and press the enter key. At this point, you’ll need to use the Right or Left arrow keys to select Disabled and press the enter key. If you don’t have a Dell computer, use the Up or down arrow keys to locate a section entitled Wake..., Wake on Lan,or Wake on Ring. The Wake on Ring section may be entitled Power on By, or Power on by Ring Modem, or Wake on Ring Modem. In any event, make the suitable selection and press the enter key. At this point, use the Up or Down arrow keys to select Disabled and press the enter key. In order to save the new settings press the F10 key, or the corresponding key that will allow you to save the new settings.

Step # 3:

Press the Esc key to exit Power Management. If necessary, press the Esc key again to exit the system BIOS and save the new settings.

If you’re computer continues to start by itself, you may want to try the following sources. Thank you for reading my article and good luck!

http://wiki.answers.com/Q/Why_would_a_computer_keep_restarting_itself_everytime_it_starts_up

http://www.techsupportforum.com/microsoft-support/windows-xp-support/207815-computer-starts-up-itself.html

http://www.vistaheads.com/forums/microsoft-public-windows-vista-performance-maintenance/49537-computer-automatically-starts-overnight-following-shut-down.html